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Author Topic: A better S.Giorgio gun sight  (Read 3490 times)

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greybeard

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A better S.Giorgio gun sight
« on: April 03, 2015, 03:10:59 AM »

Hi!

I would propose an improvement of the classic Italian gun sight, not quite well reproduced in game as shape, color and reticle size.

The basic concept was as follows:
"It is supposed to have to run the shot against a plane located 250 meters away and having a speed of 100 meters per second (360 km / h).

The projectile has an absolute velocity of 850 m / sec (the sum of its initial speed - 750 m / sec and the speed of the own aircraft that is supposed to 100 m / sec) so it takes 0.295 seconds to reach the target. As the target moves in this time of 29.5 meters, the cursor is required of 118 thousandths. In the figure the eye is supposed O: it is therefore necessary that the luminous circle has a radius that (A' B') to subtend an angle of 118 thousandths.
"



"Identical considerations apply for the small circle. In this case it is assumed, however, that the enemy aircraft is an airplane traveling with a speed of 50 m / sec (180 km / hour).
The cursor is needed 60 thousandths.

The pointer will start the firing of weapons where the center of the aircraft will cut one or the other of the circumferences of the two luminous circles respectively in the case that the speed of the opponent appreciated around 100 and 50 m / sec.

To appreciate with good accuracy the range of the shot there are three bright dots: r, c, r' (as shown).
"



"The distances cr - cr' are such as to subtend to the eye of the pointer at an angle of 28°°, angle that at 250 meters determines a length of 7 meters."



The manual continues by saying that the size of the circles with respect to the mirror varies with the distance of the pointer, it is recommended that not more than 250 millimeters.

For use, the manual says:
"The rules for aiming are: estimating speed and direction of flight of the enemy, use sighting circle on the outside or inside depending on the transverse component of the velocity is closer to 100 or 50 m / sec."






Any taker? ;)
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WxTech

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Re: A better S.Giorgio gun sight
« Reply #1 on: April 04, 2015, 01:48:48 PM »

After having built an N-2A, I have comtemplated improving some other early war gun sights, including Italian. In which planes was this sight actually installed?
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greybeard

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Re: A better S.Giorgio gun sight
« Reply #2 on: April 04, 2015, 03:20:48 PM »

FIAT CR.42, G.50, G.55(*)
Macchi C.200, C.202, C.205V(*)
Reggiane Re.2000

(*) these types could be of a later model.

More details here

Thanks,
GB
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asheshouse

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Re: A better S.Giorgio gun sight
« Reply #3 on: April 05, 2015, 03:32:08 AM »

Interesting request. Hope it attracts expert support.
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WxTech

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Re: A better S.Giorgio gun sight
« Reply #4 on: April 06, 2015, 09:57:25 AM »

It would appear that the sight shown in the illustrations above is a late variant. In my very limited *investigation* so far, the more relevant sight design for the earlier fighters has the reflector assembly mounted on a pair of vertical rods which permit to set the reflector height over a fairly large range. This appears to be the one crudely 'modelled' for the stock G50, C.R. 42, MC-200 and MC-202--in three different approaches (in my 4.08 game, anyway.)

C.R. 42: Missing the 'strap' which conforms to the reflector. This device is made to pivot downward so that an iron sight 'bead' at its crown is brought into alignment with a ring (marked on the lower reflector?). The lamp house at bottom is shown as a quite useless open box.

G50: The reflector assembly is represented by a graphic which looks more like a hand mirror design ;), and is not constructed as a 3-D object at all. Ghastly!

MC-200/202: The lamp house is too large, more so in depth, and incorrectly is made to appear to serve also as the mounting. The crash pad is too low. The MC-202 sight would appear to be too large, whereas the -200 appears to be pretty close to the correct dimensions (as gleaned from crude measurements made on an image which includes a 14X48mm AA battery.)

MC-205: In the main, not too bad. Could use some refinements.
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greybeard

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Re: A better S.Giorgio gun sight
« Reply #5 on: April 07, 2015, 02:39:29 AM »

It would appear that the sight shown in the illustrations above is a late variant.

I don't think so. Manual where I picked those images is dated 1938 (XVI of "fascist era") and titled "Type A".



It looks there where three types: A, B and C. You mentioned type "B" (the one with vertical rods and a squared basis)



here for sure fitted on a MC.202



I guess "Type A" was fitted on very early fighters, that's to say CR.42 and G.50, "Type C"(depicted below) on very late ones, that's to say MC.205 and G.55, and "Type B" on all other intermediate fighters (MC.200, MC.202).

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WxTech

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Re: A better S.Giorgio gun sight
« Reply #6 on: April 07, 2015, 03:45:53 AM »

Greybeard,
Interesting stuff. You've supplied better info than I've so far been able to glean via Google.

The type A looks to be a more elegantly executed design than the Type B, appearing to me to *look* like it's a later version. (Although its apparently parallel-to-the-reflector sun shade could result in double reflections of the reticle.)

I should look into obtaining any free 3-D software which would make the design process less onerous than my current tool, Excel, which requires much 'manual' and hence plodding, slow work. We have here two sights to make, one significantly refined (type B), and the other practically from scratch (Type A).
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Kopfdorfer

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Re: A better S.Giorgio gun sight
« Reply #7 on: April 07, 2015, 05:57:05 AM »

Great work you two!

This kind of attention to detail is what makes Il2_2015 stay on top.
I really hope you guys can get this out there.

For my 2 cents worth , mounting a different gunsight in a given aircraft was not a huge task (given certain physical requirements - ie base dimensions) , so if you were to go for only one version , I would vote for the most common variant(mid range in terms of development).

...now if your were to go at all three , well...

I love reading threads like this - whether the mods get pursued or not!

Kopfdorfer
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WxTech

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Re: A better S.Giorgio gun sight
« Reply #8 on: April 07, 2015, 07:44:50 AM »

For the Type B sight, I wonder if it might be worthwhile to design it with the 'iron' sight 'strap' in the down position, so that its bead is aligned with the small double ring pattern printed directly on the lower reflector? (This configuration was manipulated thusly in the event of both lamps burning out/failing.) This would unmask the reflector's edge, removing the slight additional obscuration. But it probably was not normally done whenever the optical reticle was operating (except perhaps in certain conditions of poor reticle visibility???).
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greybeard

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Re: A better S.Giorgio gun sight
« Reply #9 on: April 07, 2015, 09:49:38 AM »

WxTech,

I would opt for "Type B" on all variants except the last ones (MC.205V, G.55), retaining their stock gun sights.

I would design it with the 'iron' sight 'strap' in the down position. Please watch picture above: "linea di mira naturale" and "linea di mira ottica" are completely separate and do not interfere each other.

About free 3-D software, "in my previous life" (LOL) I did something with Anim8or (), please find it at the relevant link:

http://www.anim8or.com/
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WxTech

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Re: A better S.Giorgio gun sight
« Reply #10 on: April 07, 2015, 12:04:41 PM »

I thought to consider the iron sight in the down position precisely because it's obvious the two sight lines are not coincident. Note, however, that if the game's reticle mask (which in real life is actually defined by the reflected image of the collimator) were made large enough, with 6DOF one could 'scrunch' down a little lower and have the two reticle patterns superimposed. Or at least the top portion of the optical reticle would be seen such that its center would, if visible, be coincident with the printed reticle's center.

For the sake of game play and a reasonably full extent of the reticle being seen (without setting the POV quite close), a larger-than-collimator reticle mask is preferred, which will likely result in at least partial overlap of the optical and printed reticles when the POV is moved downward. But that's OK by me...

As to the more 'generic' sight model, the Type B is definitely the preferred one if only one is to be made for the C.R. 42 to MC-202 families. At least until a Type A follows on for the earliest planes.

I note in that MC-202 'pit photo you included above that the sight's lamp house is rotated nearly 90 degrees from the factory schematic's representation. I suspected such could be possible; the attachment scheme for the lamp house is cylindrical, permitting rotation and locking down via set screws which seat in a groove. This is understandable due to the lamp house's differing dimension in width compared to depth. Being able to tweak the position in rotation permits to reduce masking of instruments.

I am becoming keen to work on the Type B sight--no estimates on a date of completion. ;)
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OberstDanjeje

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Re: A better S.Giorgio gun sight
« Reply #11 on: April 08, 2015, 01:47:11 AM »

good idea, hope to see it in action ;)
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